(a) Field of the Invention
The present invention relates to a frame for a self-piercing rivet system. More particularly, the present invention relates to a frame for a self-piercing rivet system that can provide bearing capacity for joining a rivet to a plate by using an anvil die and a punch unit.
(b) Description of the Related Art
Automotive industries pay attention to environmental problems, and apply aluminum alloys and plastic materials to a vehicle body so as to reduce weight of the vehicle body and to improve fuel consumption as one of solutions that improves the environmental problems.
For this purpose, joining methods for assembling the vehicle body instead of using conventional spot welding have been researched and developed.
Recently, a self-piercing rivet using a self-piercing rivet system has been increasingly used.
According to a conventional riveting technique, joining objects such as steel sheets are joined by forming a head portion after a riveting hole is bored and a rivet is inserted into the riveting hole.
However, the rivet is press-fitted into the joining objects by hydraulic pressure or pneumatic pressure without forming the riveting hole according to the self-piercing rivet technique. At this time, the rivet is plastically deformed and joins the joining objects.
The self-piercing rivet system includes a C-shaped frame 101 mounted on a front end of an arm of a robot (not shown), a punch unit 103 formed at an upper portion of the frame 101, and an anvil unit 105 formed at a lower portion of the frame 101 corresponding to the punch unit 103, as shown in FIG. 1.
Further, the punch unit 103 includes a punch cylinder 111 and a punch housing 113, and is mounted on the frame 101 through the punch housing 113. The punch housing 113 includes a punch (not shown) operated by an operating rod of the punch cylinder 111 and a clamper 115 inside thereof.
The anvil unit 105 includes an anvil die 117, and is mounted on a lower portion of the frame 101 through a mounting rod.
The self-piercing rivet system as described above performs self-piercing riveting by operating the robot through the frame 101 mounted on the arm of the robot (not shown).
Herein, an operation force of the punch unit 103 is transmitted to a lower portion of the conventional C-shape frame 101 near to the anvil unit 105, so a large load is applied to the conventional frame 101. Thus, the conventional frame 101 should be made of steel materials in order to maintain rigidity and bear the load.
However, the conventional frame can become heavier since it is made of steel materials. Accordingly, more power for operating the robot may be required, and operation responsiveness of the robot may be decreased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.